In the data storage industry, companies utilize atomic force microscopes (AFMs) to characterize media (such as hard disks) or heads (such as recording heads). During AFM operation, an AFM probe is scanned over a surface to be characterized (see FIG. 1A), or, alternatively, the surface is scanned under the probe (see FIGS. 1B and 1C). Similar scanning techniques are used in other types of microscopy as well.
Early AFM designs used a piezotube scanner or tube scanner. These designs are problematic because the scanner is prone to bowing in the Z direction as it scans the sample in the X and Y directions, depicted graphically in FIG. 2. Error caused by bowing of a piezotube scanner varies non-systematically and can be as high as 60 nm over 100 μm of horizontal scanning range.
Current AFM manufacturers that serve the data storage industry provide metrology-grade scanners where piezotube scanners have been eliminated and replaced with flexure stages. Flexure stages can be XYZ scanners (see FIG. 1B), XY scanners to be used with separate Z scanners (see FIG. 1C), or linear scanners (X or Y axis) to be used with separate Z scanners. The typical error caused by bowing of a flexure stage is about 10 nm over 100 μm of horizontal scanning range.
nPoint, Madison, Wis., has previously succeeded in manufacturing 100-μm XY flexure scanners with out-of-plane scanner bow that can be less than 2 nm in certain limited circumstances. Minimal error on this order is now a requirement of many users of AFM technology, such as those in the data storage and semiconductor industries. Consequently, these scanners have been adopted by AFM manufacturers such as Veeco (Plainview, N.Y.) and are also sold as upgrades for existing AFMs, such as Veeco's Dimension Vx200/300 Atomic Force Profiler. In a typical configuration, the XY flexure scanner scans in the XY planes and a Veeco metrology head performs the scanning in the Z plane, as is shown in FIG. 1C.
In the above-mentioned system, the out-of-plane bow can be controlled to 2 nm if the sample is placed in the central area of the scanning platform. However, bowing can reach magnitudes between 5 and 10 nm when scanning in the periphery of the platform, such as the corners of the platform.
There is a need for flexure scanners that exhibit no greater than 2 nm bow per 100 μm of scanning range for scanning ranges up to about 1 mm.